You can add a text label to any beat using this button in the keyboard.
You can attach a dynamics marker to any beat, using the palette.
There is an option in the Score Settings to always hide these markers if you just want the sounding but don't want them to be displayed/printed.
Several accents and anti-accents are available in the keyboard popup.
A ghost note
Accents and strong accents.
Chord names and diagrams
Add a chord name or chord diagram to your compositions.
Use the Alt key of the keyboard to change the button to a chord diagram.
Chord names are attached to the measure and will be displayed at the top of the first staff.
Chord diagrams are attached to a specific staff and will be displayed only for this staff.